Steam turbines



Aug. 23, 1966 F. SWINGLEHURST 3,268,206

STEAM TURBINES Filed Oct. 14, 1963 s Sheets-Sheet 1 Aug. 23, 1966 F. SWINGLEHURST STEAM TURBINES 5 Sheets-Sheet 2 Filed Oct. 14/1963 Fig. 4

Aug. 23, 1966 F SWINGLEHURST STEAM TURBINES 5 Sheets-Sheet 5 Filed Oct. 14, 1963 United States Patent 3,268,206 STEAM TURBINES Frank Swinglehurst, Cheadle Hulme, England, assignor to Associated Electrical Industries Limited, London, England, a British company Filed Oct. 14, 1963, Ser. No. 315,842 Claims priority, application Great Britain, Oct. 19, 1962, 39,706/62 13 Claims. (Cl. 25339) This invention relates to improvements in steam turbines.

In an orthodox steam turbine the horizontal bladed rotor extends through a casing which is made in two halves joined by a horizontal joint lying in or near the horizontal plane containing the axis of the rotor. The bearings by which the rotor is supported and located are similarly split by horizontal joints, and the assembly of the turbine involves lowering the rotor onto the lower halves of the bearings, assembling the upper halves of the bearings, and putting in position the upper half of the casing.

An alternative type of turbine casing would be substantially box-shaped with an open top or an opening in the top through which the rotor could be lowered into place. Such a casing arrangement is technically attractive and is particularly advantageous in a condensing steam turbine plant, since in such a case the arrangement enables the two halves of the condenser to be located respectively on opposite sides of the turbine rotor, with their mid-height approximately level with the rotor centre line.

In a steam turbine it is necessary that the rotor bearings shall be isolated from the steam filling the turbine casing, so that in the simple case of a rotor or rotor section carried near its two ends by bearings, the bearings would be located outside the casing and the rotor would be long enough to span the distance between the bearings, so extending through both end walls of the casing. The rotor in a large turbine is upwards of twelve feet between centres of the journal bearings, and weighs upwards of seven tons. It carries blades which, when the rotor is lowered in position, must fit between fixed diaphragms with only a small clearance. In view of the weight and the need for vertical movement to enter the rotor blades between the diaphragms, it has in the past been considered essential to provide the ends of a box-like turbine casing with U-shaped apertures joining at their upper ends the opening in the top of the box, so that the rotor can be lowered vertically into the box and into its final position relative to the rotor bearings and the fixed diaphragms.

According to one aspect of the present invention, a turbine comprises a box-like casing having a removable lid or cover and a rotor arranged to extend with its axis horizontal through the casing and to be supported on bearings disposed at a level intermediate the top and the bottom of the casing, each end wall of the casing being provided with an opening, having a removable cover, extending vertically upwards from the region where the rotor shaft extends through the end wall, the opening stopping short of the top of the casing but being of such height that the rotor can be raised vertically until the parts of the rotor are clear of the fixed lower halves of the diaphragms of the turbine and then moved axially and tilted so that its axis is inclined to the horizontal to permit it to be withdrawn vertically through an opening in the top of the casing normally closed by the lid or cover.

According to another aspect of the present invention, a turbine comprises a box-like casing having a removable lid or cover and a rotor, including separable first and second end sections, arranged to extend with its axis horizontal through the casing and to be supported on bearings disposed at a level intermediate the top and the bottom of the casing, each end wall of the casing being provided with an opening, having a removable cover, extending vertically upwards from the region where the rotor shaft extends through the end wall, the opening stopping short of the top of the casing but being of such height that the associated end section of the rotor, when separated from the remainder of the rotor, can be raised vertically until the parts of the rotor section are clear of the fixed lower halves of the diaphragms of the turbine and then moved axially inwardly away from the end wall to permit it to be withdrawn upwardly, with its axis horizontal or suitably inclined to the horizontal, through an opening in the top of the casing normally closed by the lid or cover.

The expression box-like casing is used to describe a casing which is substantially in the form of a box having rectangular sides, ends and top. The casing floor shape must depend upon the arrangements for the supply of steam to the rotor and whether it is necessary to exhaust steam downwardly to subjacent condensers.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is a perspective drawing of a box-like turbine casing to which the invention has been applied;

FIGURE 2 is a sectional side elevation of a single cylinder low pressure steam turbine;

FIGURE 3 is a sectional side elevation of the turbine shown in FIGURE 2 but with the turbine rotor in the process of being removed;

FIGURE 4 is a sectional side elevation of a steam turbine having a multi-span rotor;

FIGURES 5 and 6 are sectional side elevations of the turbine shown in FIGURE 4 but showing the turbine rotor in different stages of the process of removal.

Referring first to FIGURE 1, this shows the general form of the turbine casing 1, which is in the form of a rectangular-sided box built up from flat plates welded together and having in its top an opening 3 which extends over about two thirds of the width of the box and which extends almost from end to end of the box and is normally closed by a cover or lid 5 (shown in FIGURE 2). Each end wall 7 of the casing is provided with an opening 9 the lower part 9A of which accommodates an inwardly extending frusto-conical detachable part 10 (FIG- URE 2) of the end wall and the upper part 93 of which extends vertically upwards from the region where the rotor shaft 11 extends through the end wall but stops short of the top of the casing, and is normally closed by an extension 10A of the part 10. The bottom of the box is, in the example shown, left open for the downward exhaust of steam to a condenser. If the condenser is provided inside the casing then the bottom of the box can be closed.

Referring now to FIGURE 2, the turbine rotor 13 includes the shaft 11 and a number of bladed discs 15 mounted on the shaft. Surrounding the bladed dics 15 is a turbine inner casing 17 provided with diaphragms 16 which intermesh with the rotor discs 15 and are provided with guide blades in known manner. The casing 17 consists of mating upper and lower diaphragm half sections 17A and 17B respectively. This arrangement of bladed rotor discs, inner casing and diaphragms is orthodox steam turbine practice. At each end the shaft 11 is mounted on bearings 19 which are disposed outside the turbine casing and are supported on pedestals which are separate from the casing and are not shown.

In order to remove the rotor 13 from the casing 1, the cover or lid 5 and the two detachable parts 10A are removed. The upper half sections 17A of the inner casing 17 are removed through the opening 3. The upper halves of the bearings 19 are removed. It is now possible by means of suitable lifting gear to lift the rotor 13 vertically so that the bladed rotor discs 15 slide out from between the lower halves 17B of the diaphragms. Once this has been done, one end of the rotor is raised further so that the rotor assumes the tilted position shown in FIGURE 3, whereupon it may be moved axially towards the left of that figure and upwardly to pass out through the opening 3.

Referring now to the embodiment of the invention shown in FIGURES 4 to 6, the construction is similar to that shown in FIGURE 2 with the exception that the rotor is divided into two sections 13A and 13B joined together by a bolted coupling 31, each section being similar to the rotor shown in FIGURE 2 and having associated with it an inner casing 17 similar to that shown in FIGURE 2. However, near its inner end each rotor section 13A and 13B is mounted on a bearing 33 mounted on a suitable pedestal (not shown), the pedestal and the bearings 33 being enclosed by a trunking 37 which extends upwardly through the turbine casing and at its upper end terminates in a horizontal flange by which it is clamped to the lid or cover 5, in which an aperture is formed coterminous with the inner periphery of the trunking. In this way, in use the bearings and the couplings are isolated from the steam in the turbine casing.

To remove the rotor from the casing, the lid or cover 5, and the two detachable parts A are removed. The upper halves 17A of the two inner casings 17 are removed through the opening 3. The upper part of the trunking 37 is detached and removed upwardly through opening 3. The upper halves of the bearings 19 and 33 are removed. The bolted coupling 31 is disconnected. It is now possible by means of the lifting cables 21 and 23, which are connected to a spreader 41, to lift the first rotor section 13A vertically so that the bladed rotor discs slide out from between the lower halves 17B of the associated diaphragms, to the position shown in FIG- URE 5. Once this has been done, the rotor section 13A can be moved axially to the position shown in FIGURE 6, and from that position it can be withdrawn vertically upwards through the opening 3. The second rotor section 13B can be removed in a similar manner.

By the improved construction set out above, the need for the making of a vacuum tight joint at the junction of three separate surfaces is avoided. It will be appreciated that, if the openings in the end walls were continued up to the top of the casing and the opening 3 continued to the ends of the casing so that the rotor could be lifted straight out in a vertical direction, three surfaces would meet at each of the four common junctions of an end wall, and end-wall-slot cover plate, and the lid or top cover. Such a vacuum tight joint can be made, but production difficulties would be incurred and the joint might give rise to leaks and operational difficulties in service. By the improved construction set out, it is possible to attach the top lid or cover 5 and the end wall parts 10 to the casing quite independently of one another and without any three-lane joints.

A further advantage of the improved construction set out above is that the lid need not go right to the end of the casing, so that a rigid corner piece extends across the top end edge at each end of the casing. In cases where the turbine casing is supported wholly or mainly along its side walls, for example by suitably braced brackets 51 indicated in FIGURE 1, there is a tendency by the casing to sag across the direction of its width in the absence of these rigid corner pieces, particularly when the lid or cover 5 is removed. The two transverse corner pieces render the structure much more rigid, greatly reducing distortions and deflections of the casing, making the installation of the turbine easier and reducing the likelihood of operating difliculties due to excessive deflection of the casing.

Although the rotor is shown in FIGURE 4 as being made up of two sections, in some cases three or more sections may lie within the casing 1, and in such an arrangement the two end sections are arranged and are removed as described above, while the intermediate section, or each of the intermediate sections, can be lifted out vertically through the opening in the top of the casing.

In the construction shown in FIGURES 4 to 6, two separate bearings 33 are provided respectively on opposite sides of the bolted coupling 31. In some cases it may be convenient to omit one of these bearings, so that the composite shaft is supported, near the coupling, on one side only of the shaft. When one of the shaft sections is to be removed, it will usually be most convenient first to remove the tops of the bearings, to connect the lifting tackle to the section of shaft which does not have a bearing adjacent the coupling, and with that tackle take the weight of that section of the shaft off the coupling 31. The coupling bolts can then be removed and this shaft section removed first. If for some reason it is required to remove the other shaft section first, then a temporary support must be provided for the section which is not provided with a bearing adjacent the coupling, before the coupling bolts are removed. Similar considerations apply to the case where an outer bearing is omitted and the end of the rotor is supported by an adjacent shaft to which it is coupled.

What I claim is:

1. A turbine comprising:

(a) a box-like casing;

(b) a rotor provided with sets of rotor blades and arranged to extend with its axis horizontal through the casing;

(c) bearings disposed at a level intermediate the top and the bottom of the casing, and on which the rotor is supported;

(d) diaphragm half sections provided with sets of guide blades and disposed below the rotor respectively between pairs of sets of rotor blades;

(e) two end walls to the box-like casing, formed with apertures through which end parts of the rotor extend;

(f) two removable covers, each arranged when in place to close an opening which extends vertically upwards in one of the end walls from the aperture, which opening terminates short of the top of the end wall and is of such height that the rotor can be raised vertically until all parts of the rotor are clear of the diaphragm half sections; and

(g) a removable lid arranged when in place to close an opening in the top of the turbine casing; whereby with the lid and two removable covers removed, the rotor can be moved axially and tilted so that its axis is inclined to the horizontal and withdrawn upwardly through the opening in the top of the turbine casing.

2. A turbine according to claim 1, in which the removable cover on each end wall of the casing is dished so that it projects into the interior of the casing.

3. A turbine as claimed in claim 1, in which one end of the rotor is supported by an adjacent, coaxial shaft to which it is coupled.

4. A turbine as claimed in claim 1, in which the casing is supported by support means provided on the sides of the casing parallel to the axis of the rotor.

5. A turbine comprising:

(a) a box-like casing;

(b) a rotor including separable first and second end sections, provided with sets of rotor blades and arranged to extend with its axis horizontal through the casing;

(c) bearings disposed at a level intermediate the top and the bottom of the casing, and on which the rotor is supported;

(d) diaphragm half sections provided with sets of guide blades and disposed below the rotor respectively between pairs of sets of rotor blades;

(e) two end walls to the box-like casing, formed with apertures through which end parts of the rotor extend;

(f) two removable covers, each arranged when in place to close an opening which extends vertically upwards in one of the end walls from the aperture, which opening terminates short of the top of the end wall and is of such height that the rotor can be raised vertically until all parts of the rotor are clear of the diaphragm half sections; and

(g) a removable lid arranged when in place to close an opening in the top of the turbine casing; whereby with the lid and the two removable covers removed, one of the rotor end sections can be disconnected from the remainder of the rotor and can be raised vertically until all ports of this rotor section are clear of the diaphragm half sections and then moved axially inwardly away from the end wall to permit it to be withdrawn upwardly, with its axis horizontal or suitably inclined to the horizontal, through the opening in the top of the turbine casing.

6. A turbine according to claim 5, in which each end section of the rotor in its operating position is supported, near its inner end, by at least one bearing, a chamber surrounding said bearing and which in use isolates the hearing from the elastic working fluid of the turbine, the upper part of the chamber being removable to allow withdrawal of the rotor.

7. A turbine according to claim 6, in which the chamber is open to the atmosphere outside the turbine.

8. A turbine according to claim 7, in which the chamber has an opening at its upper end which mates with a similar opening in the lid or cover of the casing.

9. A turbine according to claim 5, in which the removable cover on each end wall of the casing is dished so that it projects into the interior of the casing.

10. A turbine according to claim 5, in which one end of the rotor is supported by an adjacent coaxial shaft to which it is coupled.

11. A turbine according to claim 5, in which the casing is supported by support means provided on the sides of the casing parallel to the axis of the rotor.

12. A turbine as claimed in claim 1, including a bearing near the plane of an end wall of the casing arranged to support one end of the rotor and isolated from the interior of the casing by the removable cover for the opening in that end wall.

13. A turbine as claimed in claim 5, including a bearing near the plane of an end wall of the casing arranged to support one end of the rotor and isolated from the interior of the casing by the removable cover for the opening in that end wall.

References Cited by the Examiner UNITED STATES PATENTS 1,726,415 8/ 1929 Sharp. 1,767,279 6/ 1930 Bulkeley. 2,038,417 4/1936 Colby 230-l28 2,073,404 3/ 1937 Hobbs. 2,966,297 12/ 1960 Sperling 230-128 FOREIGN PATENTS 329,529 11/1920 Germany. 137,880 l/ 1920 Great Britain.

EDGAR W. GEOGH-EGAN, Primary Examiner.

JULIUS E. WEST, Examiner.

E. A. POWELL, JR., Assistant Examiner. 

1. A TURBINE COMPRISING: (A) A BOX-LIKE CASING; (B) A ROTOR PROVIDING WITH SETS OF ROTOR BLADES AND ARRANGED TO EXTEND WITH ITS HORIZONTAL THROUGH THE CASING: (C) BEARINGS DISPOSED AT A LEVEL INTERMEDIATE THE TOP AND THE BOTTOM OF THE CASING, AND ON WHICH THE ROTOR IS SUPPORTED; (D) DIAPHRAGM HALF SECTIONS PROVIDED WITH SETS OF GUIDE BLADES AND DISPOSED BELOW THE ROTOR RESPECTIVELY BETWEEN PAIRS OF SETS OF ROTOR BLADES; (E) TWO END WALLS TO THE BOX-LIKE CASING, FORMED WITH APERTURES THROUGH WHICH END PARTS OF THE ROTOR EXTEND; (F) TWO REMOVABLE COVERS, EACH ARRANGED WHEN IN PLACE TO CLOSE AN OPENING WHICH EXTENDS VERTICALLY UPWARDS IN ONE OF THE END WALLS FROM THE APERTURE, WHICH OPENING TERMINATES SHORT TO THE TOP OF THE END WALL AND IS OF SUCH HEIGHT THAT THE ROTOR CAN BE RAISED VERTICALLY UNTIL ALL PARTS OF THE ROTOR ARE CLEAR OF THE DIAPHRAGM HALF SECTIONS; AND 